Mesencephalic astrocyte-derived neurotrophic factor inhibits neuroinflammation through autophagy-mediated α-synuclein degradation

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder marked by the progressive loss of dopamine neurons in the substantia nigra. α-synuclein (SNCA) aggregation-induced microglia activation and neuroinflammation play vital role in the pathology of PD. Our previous studies showed that mesencephalic astrocyte-derived neurotrophic factor (MANF) could inhibit SNCA accumulation and Lipopolysaccharides (LPS)-induced neuroinflammation, but the specific molecular mechanism remains unclear. In this study, we showed that knock-down the expression of MANF leads to the up-regulation of inflammatory factor tumor necrosis factor-α (TNF-α). Exogenous MANF protein inhibits LPS-induced neuroinflammation in BV2 cells. Additionally, our results indicated that knock-down of the expression of MANF triggered autophagic pathway dysfunction, while exogenous addition of MANF protein or using adeno-associated virus 8 (AAV8) mediated MANF over-expression could activate the autophagic system and subsequently suppress SNCA accumulation. Furthermore, using autophagy inhibitor to block autophagic flux, we found that MANF prevented neuroinflammation by autophagy-mediated SNCA degradation. Collectively, this study indicated that MANF has potential therapeutic value for PD. Autophagy and its role in MANF-mediated anti-inflammatory properties may provide new sights that target SNCA pathology in PD.